Identification And Functional Analysis Of Pathogenic Genes Associated With Pathological Myopia And FSGS

With rapid development of new generation sequencing technology,the whole exome sequencing is increasingly used in the screening of various pathogenic genes of human genetic disease.Genetic factors play an important role in the development of pathological myopia,one of the leading causes of blindness.56 individuals from 10 pathological myopia families and 29 unrelated pathological myopia patients were selected for whole exome sequencing.We successfully screened the gene PAMY1 mutated in four pathological myopia families and in one sporadic patients.All the variants are heterozygous and absent from the control cohort of 590 healthy individuals or common db SNP database.PAMY1 encodes a seven transmembrane protein that belongs to the adhesion GPCR family and is likely involved in complex processes including cell adhesion and signal transduction.PAMY1 was expressed in cornea,retina,and lens epithelial cells of mice.The cornea stromal of Pamy1 knockout mice was significantly abnormal,the connection between keratocytes and collagen fibrils was looser,and the cell membrane was clearly visible.The migration and adhesion ability of the PAMY1 mutanted lens epithelial cells was decreased significantly.These findings provide an important clue to reveal how PAMY1 participated in the pathogenesis of pathologic myopia.Focal segmental glomerulosclerosis(FSGS)is a clinicopathologic syndrome with lesions of FSGS and foot-process effacement clinically characterized by massive proteinuria and renal failure.Recent findings that mutations of multiple podocyte related genes can lead to familial FSGS greatly enhanced our understandings of glomerular diseases.However,the mutation rate of these genes based on the report was very low in Asian FSGS patients.We recruited 40 FSGS families and 50 sporadic FSGS patients with Asian descent in this study.By using whole exome sequence and multiple PCR sequence,we identified six independent missense mutations of COL4A3 which encodes ?3 collagen chains of type IV collagen,the main structural component of glomerular basement membranes(GBM).Of these mutations,five were segregated with FSGS and kidney injury in FSGS families,one was identified in a sporadic FSGS patient.All the variants are heterozygous and absent from the healthy control cohort.Patients with COL4A3 mutations had similar clinical features.In four index patients of FSGS families,we found small segmental thinning of the GBM but elsewhere was apparently normal.In conclusion,our finding demonstrates a new subgroup of FSGS caused by the heterozygous mutations of COL4A3.The mutation rate is as high as 12.5% in Asian familial FSGS patients.Thus,screening for COL4A3 mutations in Chinese FSGS familial patients is suggested.